US4025489A - Utilization of bisphenol-A from the alkaline phase generated in the production of polycarbonates - Google Patents

Utilization of bisphenol-A from the alkaline phase generated in the production of polycarbonates Download PDF

Info

Publication number
US4025489A
US4025489A US05/544,246 US54424675A US4025489A US 4025489 A US4025489 A US 4025489A US 54424675 A US54424675 A US 54424675A US 4025489 A US4025489 A US 4025489A
Authority
US
United States
Prior art keywords
solvent
aqueous alkaline
phosgene
bpa
solution
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US05/544,246
Other languages
English (en)
Inventor
John V. Bailey
Thomas H. Cleveland
Emanuel W. Wirfel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bayer Corp
Original Assignee
Mobay Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mobay Corp filed Critical Mobay Corp
Priority to US05/544,246 priority Critical patent/US4025489A/en
Priority to CA242,479A priority patent/CA1049565A/en
Priority to DE19762602366 priority patent/DE2602366A1/de
Priority to JP51006040A priority patent/JPS5930726B2/ja
Priority to NLAANVRAGE7600775,A priority patent/NL181202C/xx
Priority to FR7602152A priority patent/FR2298568A1/fr
Application granted granted Critical
Publication of US4025489A publication Critical patent/US4025489A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G64/00—Macromolecular compounds obtained by reactions forming a carbonic ester link in the main chain of the macromolecule
    • C08G64/40—Post-polymerisation treatment
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G64/00—Macromolecular compounds obtained by reactions forming a carbonic ester link in the main chain of the macromolecule
    • C08G64/20—General preparatory processes
    • C08G64/22—General preparatory processes using carbonyl halides
    • C08G64/24—General preparatory processes using carbonyl halides and phenols

Definitions

  • polycarbonate resins and methods for the preparation thereof are well-known to the art.
  • polycarbonate resins are conventionally prepared by reacting an acid chloride of a carbonic acid with a diphenylolalkane in a heterogeneous liquid reaction medium comprising an aqueous alkaline solution containing a reaction catalyst and an inert organic solvent.
  • the polycarbonate resin preferably comprises the reaction product of carbonyl chloride, i.e., phosgene, and 2,2-(4,4'-dihydroxydiphenyl)-propane, more commonly referred to as bisphenol-A, hereafter BPA, in a molar ratio of between about 1.1 to about 1.2 mols of phosgene per mol of BPA.
  • BPA bisphenol-A
  • diphenylolalkanes may also be used, such as, for example: (4,4'-dihydroxydiphenyl)-methane; 1,1-(4,4'-dihydroxy-diphenyl)-cyclohexane; 1,1-(4,4'-dihydroxy-3,3'-dimethyl-diphenyl)-cyclohexane; 2,2-(2,2'dihydroxy-4,4'-di-tert-butyl-diphenyl)-propane; 1,1-(2,2'-dihydroxy-4,4'-dimethyl-diphenyl)-butane; 3,4-(4,4'-dihydroxy-diphenyl)-hexane; 1,1-(4,4'-dihydroxy-diphenyl)-1-phenyl-ethane; 2,2'-(4,4'-dihydroxy-diphenyl)-butane; 2,2-(4,4'-dihydroxydiphenyl)-methane;
  • the aqueous alkaline phase of the heterogeneous medium generally comprises aqueous solutions of water soluble alkaline materials or aqueous dispersions of water insoluble alkaline materials.
  • inorganic alkaline materials which function as hydrogen halide acceptors.
  • Exemplary of such materials are the oxides, hydroxides and carbonates of alkaline earth metals and alkali metals, such as, sodium, potassium, calcium, barium, strontium, magnesium and the like.
  • a concentrated aqueous solution of sodium hydroxide is used having a sodium hydroxide content of from about 40 to about 60 percent by weight. Generally, about one mol of sodium hydroxide is used per mol of phosgene.
  • the inert organic solvent is one in which the polycarbonate resin is soluble, sufficient solvent being used to produce about a 14 percent by weight solution of polycarbonate in the solvent.
  • Typical of such solvents are methylene chloride, ethylene chloride; benzene; monochlorobenzene; methyl cyclohexane; cyclohexane; toluene; xylene; chloroform; carbon tetrachloride; trichloroethylene; perchloroethylene; and the like, as well as mixtures thereof.
  • catalysts are trimethylamine; triethylamine; dimethylaniline; diethylaniline; dimethylcyclohexylamine; pyridine and the like, as well as the corresponding hydrochlorides.
  • Suitable catalysts are tetramethylammonium hydroxide; triethyloctadecylammonium chloride; trimethylbenzylammonium fluoride; triethyl-benzylammonium chloride; dimethyldodecylammonium chloride; dimethylbenzylphenylammonium chloride; trimethylcyclohexylammonium bromide; N-methyl pyridinium chloride; N-methyl morpholine; and the like.
  • a preferred catalyst is triethylamine and is used in amounts ranging from 0.1 to about 0.3 percent by weight based on the weight of polycarbonate and is preferably added after the initial reaction between the BPA and phosgene and prior to phase separation.
  • the reaction between the BPA and phosgene occurs at the phase boundary or interface of the solvent/aqueous phases, the organic solvent retaining the polycarbonate resin thus formed in solution.
  • the reaction medium is separated into two immiscible phases.
  • the organic solvent phase containing the dissolved resin is further processed by conventional means such as, for example, distillation, non-solvent addition or the like to recover the resin and the aqueous alkaline phase is discharged to waste.
  • the amount of BPA in the aqueous alkaline phase can vary between about 0.01 to about 0.7 percent by weight and is usually between about 0.1 to about 0.3 percent by weight with an average BPA content of about 0.25 percent by weight. It would be desirable if this BPA could be recovered and used in the production of additional polycarbonate, for in a full-scale operation, the amount of BPA contained in the alkaline layer is significant. For example, in a plant having a polycarbonate production capacity of about 60 million pounds per year, the excess BPA in the alkaline layer averages about 113 pounds per hour. Thus the recovery and utilization of this unreacted, excess BPA results in a two-fold advantage in that significant savings in the cost of starting materials will be realized and the organic materials content of the alkaline waste will be significantly reduced.
  • an object of this invention to provide a means of recovering unreacted BPA from the aqueous alkaline phase generated in the production of polycarbonates. It is another object of this invention to provide a means of continuously recovering said BPA and returning the recovered BPA to the main reaction stream. A further object of this invention is to reduce the level of organic materials in the aqueous alkaline phase generated in the production of polycarbonates by recovering, in a usable form, a substantial portion of the unreacted BPA contained therein. An additional object of this invention is to provide a more efficient, more economical means of recovering unreacted BPA from the aqueous alkaline phase generated in the production of polycarbonate resin devoid of the disadvantages of the prior art.
  • the invention comprises phosgenating the aqueous alkaline layer generated in the production of polycarbonate resin, the phosgene reacting with the unreacted BPA contained in the aqueous alkaline layer to produce a low molecular weight polymer having a high level of chlorocarbonate end groups and returning a solvent solution of the low molecular weight polymer to the main reaction stream.
  • FIG. 1 is a flow sheet which depicts generally a typical polycarbonate production process embodying the invention.
  • FIG. 2 is a graph showing the effect of phosgene/BPA molar ratio on BPA recovery from the aqueous alkaline phase.
  • Polycarbonate starting materials are reacted in a primary reaction stage, the relative proportions of materials being selected in a manner well known to the art and described, for example, in U.S. Pat. Nos. 3,043,800; 3,046,255; 3,213,059; 3,173,891; 3,240,755 and 3,530,094.
  • the reaction mixture is separated into two immiscible phases in a phase separation stage by means of a decanter or the like.
  • the organic solvent phase containing the dissolved polycarbonate resin is drawn-off for further processing to recover and refine the finished resin.
  • the aqueous alkaline phase containing unreacted BPA is conveyed to a secondary reaction stage to which is fed phosgene and solvent.
  • the phosgene is dissolved in the solvent feed to the secondary reaction stage.
  • the phosgene reacts with the unreacted BPA in the aqueous alkaline phase, the reaction occurring at the interface of the solvent/aqueous phases, to form a low molecular weight polymer having a high level of chlorocarbonate end groups due to the low level of BPA in the aqueous alkaline phase.
  • the low molecular weight polymer is dissolved in the solvent and the solvent solution is separated in a phase separation stage and returned to the main reaction stream wherein an excess of BPA is present to completely react the chlorocarbonate end groups on the low molecular weight polymer.
  • the catalyst being preferably added to the reaction mixture after the initial reaction in the primary reaction stage and prior to the introduction of the reaction mixture into the primary phase separation stage.
  • the catalyst may be added between the secondary reaction stage and the secondary phase separation stage, the catalyst then being introduced into the main reaction stream along with the solvent solution of the low molecular weight polymer formed in the secondary reaction stage and recycled to the main stream.
  • the addition of the catalyst between the secondary reaction stage and the secondary phase separation stage also enhances the reaction between the phosgene and unreacted, excess BPA in the aqueous alkaline layer resulting in increased removal of the unreacted BPA for a given set of reaction conditions.
  • the amount of catalyst is based on the quantity of aqueous alkaline layer fed to the secondary reaction stage, about 0.02 percent by weight of catalyst being added based on the feed rate of aqueous alkaline layer. For example, assuming that 100 lb/hour of aqueous alkaline layer containing 0.25 percent by weight BPA is fed to the secondary reaction stage, 0.02 lb/hr. of, for example, triethylamine catalyst would be used, resulting in a molar ratio of catalyst to BPA of about 0.22 to 1. It is surprising that the low molecular weight polymer would be formed in the presence of such a relatively large amount of catalyst since it is well known that using excessive amounts of catalyst could hinder rather than promote a chemical reaction.
  • the BPA content in the alkaline aqueous layer may be reduced to less than 0.01 percent by weight, in which case a molar ratio of at least about 2.5 mols of phosgene per mol of BPA has proved to be optimum.
  • sufficient solvent be used to produce less than 5.0 percent and preferably about a 2.5 percent by weight solution of low molecular weight polymer in the solvent. If less solvent is used, for example, only sufficient solvent to produce about a 5.0 percent by weight polymer solution, BPA recovery is retarded.
  • the extent of BPA recovery is also a function of residence time in the secondary reaction stage, the more time allowed for reaction, the more BPA is converted to the low molecular weight polymer.
  • the residence time in the reactor should not, as a practical matter, exceed about 5 or 6 minutes and preferably not more than about 2 minutes.
  • a polycarbonate resin is prepared in a conventional manner by reacting in a primary reaction stage about 1.1 to about 1.2 mols of phosgene per mol of BPA in a heterogeneous liquid medium comprising an aqueous caustic solution and a mixed organic solvent.
  • the aqueous caustic solution contains about 40 to 60 percent by weight sodiumhydroxide and is used in such quantity so that about 1 mol of NaOH is present for each mol of phosgene.
  • Sufficient mixed solvent is used so as to produce an about 14 percent by weight solution of polycarbonate in the mixed solvent.
  • the residence time in the primary reaction stage is about 2 to 5 minutes after which the reaction mixture is charged to a primary separation stage.
  • a typical aqueous alkaline phase generated in the production of a polycarbonate resin according to Example 1 has the following analysis:
  • the aqueous alkaline phase is fed to the secondary reaction stage at a rate of about 744 lbs/hr, which corresponds to about 0.0091 lb-mols/hr of BPA.
  • about 0.02275 lbs-mols/hr of phosgene dissolved in a mixed solvent is fed to the secondary reaction stage, sufficient mixed solvent being used such that the low molecular weight polymer resulting from the reaction of phosgene and BPA will form about a 2.5 percent by weight solvent solution.
  • the molar ratio of phosgene to BPA is about 2.5 to 1 and the residence time in the secondary reaction stage is about 2 minutes.
  • reaction mixture is then fed to the secondary separation stage to effect phase separation, the residence time in the secondary phase separation stage being about 2 minutes.
  • the solvent phase containing the dissolved low molecular weight polymer is returned to the main reaction stream and the aqueous alkaline phase is discharged to waste.
  • the polymer produced has a low molecular weight and contains a high level of chlorocarbonate end groups, therefore, it is readily reacted in the main reaction stream as the excess of BPA in the main stream will completely react the chlorocarbonate end groups.
  • the quantity of solvent used in the secondary reaction stage is a factor in optimizing the extent of recovery of BPA from the aqueous alkaline layer and sufficient solvent should be used to provide a solution of low molecular weight polymer of less than 5 percent by weight and preferably about 2.5 percent by weight.
  • a catalyst can be added either between the primary reaction stage and the primary separation stage or between the secondary reaction stage and the secondary separation stage.
  • the catalyst In the former case, between about 0.06 and 0.40 percent by weight of catalyst is used based on the weight of polycarbonate resin and in the latter case, about 0.02 percent by weight of catalyst is used based on the weight of aqueous alkaline layer, and the catalyst enters the main reaction stream along with the solvent solution of the low molecular weight polymer.
  • the catalyst to BPA molar ratio is quite high and it is surprising that BPA recovery is enhanced as it is known that an excessive amount of catalyst could inhibit rather than accelerate a chemical reaction.
  • the optimum molar ratio of phosgene to BPA in the aqueous alkaline layer is about 2.5 to 1.
  • a low phosgene/BPA ratio results in less efficient BPA removal while BPA removal is not significantly improved at phosgene/BPA molar ratios much in excess of 2.5 to 1.
  • the use of excessive amounts of phosgene are to be avoided as the same increases the acidity of the aqueous alkaline layer and could cause problems in the waste treatment facility in which the aqueous alkaline layer is treated subsequent to BPA removal and prior to discharge from the plant.
  • the invention provides a relatively simple and straight-forward means of removing excess, unreacted BPA from the aqueous alkaline phase generated in the production of polycarbonates.
  • the examples further illustrate that the extent of BPA removal is enhanced by a number of factors, notably the amount of solvent fed to the secondary reaction stage, the addition of a catalyst in the BPA removal stage and the molar ratio of phosgene to BPA in the aqueous alkaline phase.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Polyesters Or Polycarbonates (AREA)
US05/544,246 1975-01-27 1975-01-27 Utilization of bisphenol-A from the alkaline phase generated in the production of polycarbonates Expired - Lifetime US4025489A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US05/544,246 US4025489A (en) 1975-01-27 1975-01-27 Utilization of bisphenol-A from the alkaline phase generated in the production of polycarbonates
CA242,479A CA1049565A (en) 1975-01-27 1975-12-23 Separation of bisphenol-a from the alkaline phase generated in the production of polycarbonates
DE19762602366 DE2602366A1 (de) 1975-01-27 1976-01-22 Rueckgewinnung von diphenylolalkanen aus der bei der herstellung von polycarbonaten entstehenden alkalischen phase
JP51006040A JPS5930726B2 (ja) 1975-01-27 1976-01-23 ポリカ−ボネ−ト樹脂の製造方法
NLAANVRAGE7600775,A NL181202C (nl) 1975-01-27 1976-01-26 Continue werkwijze voor de bereiding van macromoleculaire polycarbonaten.
FR7602152A FR2298568A1 (fr) 1975-01-27 1976-01-27 Procede po

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US05/544,246 US4025489A (en) 1975-01-27 1975-01-27 Utilization of bisphenol-A from the alkaline phase generated in the production of polycarbonates

Publications (1)

Publication Number Publication Date
US4025489A true US4025489A (en) 1977-05-24

Family

ID=24171385

Family Applications (1)

Application Number Title Priority Date Filing Date
US05/544,246 Expired - Lifetime US4025489A (en) 1975-01-27 1975-01-27 Utilization of bisphenol-A from the alkaline phase generated in the production of polycarbonates

Country Status (6)

Country Link
US (1) US4025489A (enrdf_load_stackoverflow)
JP (1) JPS5930726B2 (enrdf_load_stackoverflow)
CA (1) CA1049565A (enrdf_load_stackoverflow)
DE (1) DE2602366A1 (enrdf_load_stackoverflow)
FR (1) FR2298568A1 (enrdf_load_stackoverflow)
NL (1) NL181202C (enrdf_load_stackoverflow)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4346210A (en) * 1977-08-09 1982-08-24 Bayer Aktiengesellschaft Process for the preparation of polycarbonates catalyzed by cyclic aza compounds
US4367330A (en) * 1979-09-20 1983-01-04 Bayer Aktiengesellschaft Process for the preparation of aromatic polycarbonates by the phase boundary process
US4638077A (en) * 1984-11-29 1987-01-20 General Electric Company Method for the preparation of chloroformate compositions
US4649210A (en) * 1985-09-23 1987-03-10 General Electric Company Reducing phosgenation reaction temperatures
US4737573A (en) * 1986-10-10 1988-04-12 General Electric Company Method for polymerizing aromatic bischloroformate composition to polycarbonate
US5317043A (en) * 1990-07-27 1994-05-31 Belland Ag Process for the recovery of polymers dissolvable in aqueous alkaline or acid media
US5376741A (en) * 1992-11-20 1994-12-27 Bayer Aktiengesellschaft Process for the preparation of polycarbonates
US5508375A (en) * 1992-12-10 1996-04-16 Bayer Aktiengesellschaft Process for the preparation of polycarbonates
USRE35499E (en) * 1988-11-16 1997-04-29 The Dow Chemical Company Elimination of monocarbonate from polycarbonate
CN1037688C (zh) * 1992-12-10 1998-03-11 拜尔公司 聚碳酸酯的制备方法
US5876851A (en) * 1993-05-19 1999-03-02 Teijin Limited Film from polycarbonate, polyester to be laminated on metal
US6420517B1 (en) * 2001-02-06 2002-07-16 General Electric Company Process for resin phase separation by plate decantation

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3028365A (en) * 1953-10-16 1962-04-03 Bayer Ag Thermoplastic aromatic polycarbonates and their manufacture
US3046255A (en) * 1957-06-20 1962-07-24 Pittsburgh Plate Glass Co Process for preparing polycarbonates
US3437639A (en) * 1965-09-10 1969-04-08 Eastman Kodak Co Process for purifying polycarbonates
US3646102A (en) * 1968-08-28 1972-02-29 Idemitsu Kosan Co Method for continuously preparing polycarbonate oligomer
US3787359A (en) * 1971-01-15 1974-01-22 Basf Ag Continuous manufacture of high molec-ular weight linear polycarbonates

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3240755A (en) * 1960-12-29 1966-03-15 Allied Chem Process for the preparation of polycarbonates

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3028365A (en) * 1953-10-16 1962-04-03 Bayer Ag Thermoplastic aromatic polycarbonates and their manufacture
US3046255A (en) * 1957-06-20 1962-07-24 Pittsburgh Plate Glass Co Process for preparing polycarbonates
US3437639A (en) * 1965-09-10 1969-04-08 Eastman Kodak Co Process for purifying polycarbonates
US3646102A (en) * 1968-08-28 1972-02-29 Idemitsu Kosan Co Method for continuously preparing polycarbonate oligomer
US3787359A (en) * 1971-01-15 1974-01-22 Basf Ag Continuous manufacture of high molec-ular weight linear polycarbonates

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4346210A (en) * 1977-08-09 1982-08-24 Bayer Aktiengesellschaft Process for the preparation of polycarbonates catalyzed by cyclic aza compounds
US4367330A (en) * 1979-09-20 1983-01-04 Bayer Aktiengesellschaft Process for the preparation of aromatic polycarbonates by the phase boundary process
US4638077A (en) * 1984-11-29 1987-01-20 General Electric Company Method for the preparation of chloroformate compositions
US4649210A (en) * 1985-09-23 1987-03-10 General Electric Company Reducing phosgenation reaction temperatures
US4737573A (en) * 1986-10-10 1988-04-12 General Electric Company Method for polymerizing aromatic bischloroformate composition to polycarbonate
USRE35499E (en) * 1988-11-16 1997-04-29 The Dow Chemical Company Elimination of monocarbonate from polycarbonate
US5317043A (en) * 1990-07-27 1994-05-31 Belland Ag Process for the recovery of polymers dissolvable in aqueous alkaline or acid media
US5376741A (en) * 1992-11-20 1994-12-27 Bayer Aktiengesellschaft Process for the preparation of polycarbonates
CN1037445C (zh) * 1992-11-20 1998-02-18 拜尔公司 聚碳酸酯的制备工艺
US5508375A (en) * 1992-12-10 1996-04-16 Bayer Aktiengesellschaft Process for the preparation of polycarbonates
CN1037688C (zh) * 1992-12-10 1998-03-11 拜尔公司 聚碳酸酯的制备方法
US5876851A (en) * 1993-05-19 1999-03-02 Teijin Limited Film from polycarbonate, polyester to be laminated on metal
US6420517B1 (en) * 2001-02-06 2002-07-16 General Electric Company Process for resin phase separation by plate decantation

Also Published As

Publication number Publication date
FR2298568B1 (enrdf_load_stackoverflow) 1979-08-24
DE2602366C2 (enrdf_load_stackoverflow) 1988-02-25
DE2602366A1 (de) 1976-07-29
FR2298568A1 (fr) 1976-08-20
NL181202B (nl) 1987-02-02
NL7600775A (nl) 1976-07-29
NL181202C (nl) 1987-07-01
JPS5930726B2 (ja) 1984-07-28
JPS51100191A (enrdf_load_stackoverflow) 1976-09-03
CA1049565A (en) 1979-02-27

Similar Documents

Publication Publication Date Title
US4025489A (en) Utilization of bisphenol-A from the alkaline phase generated in the production of polycarbonates
US5254666A (en) Process for production of alkaline or alkaline-earth metal terephthalate or of terephthalic acid, of high purity, from polyol polyterephthalate and in particular from waste of an ethylene gylcol polyterephthalate
US5336750A (en) Process for the preparation of polycarbonates
EP0456052A2 (en) A method for making end-capped polycarbonates from bisphenol monochloroformate polycarbonate oligomers
US7534851B2 (en) Method for purifying wastewater
JP3962836B2 (ja) ビスフェノールａの生産
EP0630878A1 (en) Process for the production of bisphenol
JPH07196582A (ja) スクラップの芳香族ポリカーボネートから有用なビスヒドロキシ芳香族有機化合物とビスアリールカーボネートを回収する方法
JP3422647B2 (ja) ポリカ−ボネ−トより炭酸ジアルキルとビスフェノ−ルとを得る方法
JPH0768334B2 (ja) カーボネートオリゴマーの連続的製造方法
US4413103A (en) Halogen-containing polycarbonate resin and process for producing same
JP4365592B2 (ja) ポリエステル廃棄物からの有効成分回収方法
US4101590A (en) Process for separation and purification of vinylphenol
JP2004277396A (ja) 芳香族ポリカーボネートから芳香族ジヒドロキシ化合物と炭酸ジアルキルを得る方法
US5393916A (en) Inhibition of dioxane formation during recovery of glycols from polyester resins
CA1171594A (en) Method for preparation of aromatic polyesterpolycarbonate
US4324665A (en) Process for recovering bromine from waste liquid
JPH02147628A (ja) ポリカーボネート系化合物の製造方法
KR970042469A (ko) 테레프탈산의 제조방법(1)
US5158651A (en) Process of centrifugally removing inorganic compounds from polyester glycol recovery bottoms
JPS6057444B2 (ja) 多価フエノ−ルのポリグリシジルエ−テルの製法
JP2798293B2 (ja) フェノール類の回収方法
JP3350696B2 (ja) ポリエチレンテレフタレ−トよりテレフタル酸とエチレングリコールとを回収する方法
JPH06329782A (ja) ポリカーボネートの製造法
US4510334A (en) Method of preparing alkalihalide free oligomeric, brominous xylylene bisphenol ethers